The exposure via Level One Robotics, which provides industrial automation services, came through rsync, a common file transfer protocol that’s used to backup large data sets, according to UpGuard Cyber Risk. The data breach was first reported by the New York Times.

According to the security researchers, restrictions weren’t placed on the rsync server. This means that any rsync client that connected to the rsync port had access to download this data. UpGuard Cyber Risk published its account of how it discovered the data breach to show how a company within a supply chain can affect large companies with seemingly tight security protocols.

This means if someone knew where to look they could access trade secrets closely protected by automakers. It’s unclear if any nefarious actors actually got their hands on the data. At least one source at an affected automaker told TechCrunch it doesn’t not appear that sensitive or proprietary data was exposed.

UpGuard’s big takeaway in all of this: rsync instances should be restricted by IP address. The researchers also suggest that user access to rsync be set up so that clients have to authenticate before receiving the dataset. Without these measures, rsync is publicly accessible, the researchers said.

The breach exposed 157 gigabytes of data—a treasure trove of 10 years of assembly line schematics, factory floor plans and layouts, robotic configurations and documentation, ID badge request forms, VPN access request forms. The breach even included sensitive non-disclose agreements, including one from Tesla.

Personal details of some Level One employees, including scans of driver’s licenses and passports, and Level One business data, including invoices, contracts, and bank account details.

The security team discovered the breach July 1. The company successfully reached Level One by July 9 and the exposure was closed by the following day.